#!/usr/bin/env python
# encoding: utf-8
# @author: Lin Han
# @contact: voldemort22@126.com
# @file: security_tools.py
# @time: 2021/5/19 16:30
# @desc:
from datetime import datetime, timedelta
from typing import Optional

from fastapi import Depends, FastAPI, HTTPException, status
from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
from jose import JWTError, jwt

from passlib.context import CryptContext

from pydantic import BaseModel

# to get a string like this run:
# openssl rand -hex 32
SECRET_KEY = "aa81443b8dd48188a480e64510305229813caf945b2ce1c4412257d976f4d83a"
ALGORITHM = "HS256"
ACCESS_TOKEN_EXPIRE_MINUTES = 30

fake_users_db = {
    "johndoe": {
        "username": "johndoe",
        "full_name": "John Doe",
        "email": "johndoe@example.com",
        "hashed_password": "$2b$12$EixZaYVK1fsbw1ZfbX3OXePaWxn96p36WQoeG6Lruj3vjPGga31lW",
        "disabled": False,
    }
}


class Token(BaseModel):
    access_token: str
    token_type: str


class TokenData(BaseModel):
    username: Optional[str] = None


class User(BaseModel):
    username: str
    email: Optional[str] = None
    full_name: Optional[str] = None
    disabled: Optional[bool] = None


class UserInDB(User):
    hashed_password: str


pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")

oauth2_scheme = OAuth2PasswordBearer(tokenUrl="token")

app = FastAPI()


def verify_password(plain_password, hashed_password):
    """
    验证原始密码和哈稀密码是不是同一个密码。
    :param plain_password:
    :param hashed_password:
    :return:
    """
    return pwd_context.verify(plain_password, hashed_password)


def get_password_hash(password):
    """
    获取哈希后的密码。
    :param password:
    :return:
    """
    return pwd_context.hash(password)


def get_user(db, username: str):
    """
    通过用户名获取一整条用户数据
    :param db:
    :param username:
    :return:
    """
    if username in db:
        user_dict = db[username]
        return UserInDB(**user_dict)


def authenticate_user(fake_db, username: str, password: str):
    """
    认证用户
    :param fake_db:
    :param username:
    :param password:
    :return:
    """
    user = get_user(fake_db, username)
    if not user:
        return False
    if not verify_password(password, user.hashed_password):
        return False
    return user


def create_access_token(data: dict, expires_delta: Optional[timedelta] = None):
    to_encode = data.copy()
    if expires_delta:
        expire = datetime.utcnow() + expires_delta
    else:
        expire = datetime.utcnow() + timedelta(minutes=15)
    to_encode.update({"exp": expire})
    encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
    return encoded_jwt


async def get_current_user(token: str = Depends(oauth2_scheme)):
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="Could not validate credentials",
        headers={"WWW-Authenticate": "Bearer"},
    )
    try:
        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
        username: str = payload.get("sub")
        if username is None:
            raise credentials_exception
        token_data = TokenData(username=username)
    except JWTError:
        raise credentials_exception
    user = get_user(fake_users_db, username=token_data.username)
    if user is None:
        raise credentials_exception
    return user


async def get_current_active_user(current_user: User = Depends(get_current_user)):
    if current_user.disabled:
        raise HTTPException(status_code=400, detail="Inactive user")
    return current_user

